Convertible roof actuation mechanism

ABSTRACT

A convertible roof actuation mechanism includes a pliable roof cover, a top stack mechanism supporting the roof cover, and at least one roof bow of the top stack mechanism independently movable relative to the remainder of the top stack mechanism for selectively reducing and increasing tension of the roof cover during latching. Another aspect of the present invention provides a single driving mechanism, for each side of the vehicle, to operate both the tension relieving roof bow and the top stack mechanism.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates generally to automotive vehicle convertible roofsand more particularly to a convertible roof actuation mechanism.

Traditional soft-top convertible roofs for automotive vehicles typicallyemploy four or five roof bows, having an inverted U-shape, spanningtransversely across the vehicle for supporting a vinyl, canvas orpolyester fiber pliable roof cover. The number one roof bow is mountedto a pair of front roof rails and is typically latched to a stationaryfront header panel of the automotive vehicle body disposed above awindshield. A number two roof bow is typically mounted to a pair ofcenter roof rails which are pivotably coupled to the front roof rails.Furthermore, the number three, four and optional five roof bows arecommonly mounted to a pair of rear roof rails which are pivotablycoupled to the center roof rails. For example, reference should be madeto U.S. Pat. Nos. 5,338,085 entitled "Folding Top for Motor Vehicles"which issued to Guckel et al. on Aug. 16, 1994; 5,225,747 entitled"Single-Button Actuated Self-Correcting Automatic Convertible Top" whichissued to Helms et al. on Jul. 6, 1993; 5,161,852 entitled "ConvertibleTop with Improved Geometry" which issued to Alexander et al. on Nov. 10,1992; 4,948,194 entitled "Flexible Roof for a Convertible Motor Vehicle,Provided with a Safety Hook for the Rear Arch of the Roof Frame" whichissued to Dogliani on Aug. 14, 1990; 4,720,133 entitled "Convertible TopStructure" which issued to Alexander et al. on Jan. 19, 1988; 4,537,440entitled "Vehicle with a Convertible Top" which issued to Brockway etal. on Aug. 27, 1985; and 2,580,486 entitled "Collapsible Top forVehicles" which issued to Vigmostad on Jan. 1, 1952.

Traditional soft-top convertible roofs possess an inherent driftproblem. In other words, when the convertible roof is moved to its fullyraised position, the forwardmost or number one roof bow is positionedagainst the front header panel for subsequent latching. However, thestretched fabric cover acts to pull the number one roof bow in anunintended and undesired rearward direction such that it drifts awayfrom the front header. This drifting situation is especially apparent innew convertible roofs. Accordingly, the vehicle occupant must thenphysically pull down upon a handle attached to the number one roof bowand hold it against the front header panel for subsequent latching. Thismanual action presents a crude and unrefined operational perception.This drifting problem is also present between a rearmost or number fiveroof bow and an adjacent tonneau cover. The number five roof bow andattached rear edge of the cover are often raised to an upward positionby separate actuators while the tonneau cover is returned from asubstantially vertical position to a substantially horizontal position;the number five roof bow is then pivoted to its lowered position againstan upper surface of the tonneau cover for latching thereto. However, thestretched fabric covering tends to pull the number five roof bow in aforward manner thereby causing it to drift away from the tonneau cover.This situation is inconvenient to remedy due to the difficulty of anoccupant accessing this rear area when seated in the front seat.

Notwithstanding, U.S. Pat. No. 5,385,381 entitled "Vehicle Roofs," whichissued to Moore et al. on Jan. 31, 1995, employs a moving number fourroof bow to tension a fabric cover. However, this patent disclosesdirectly attaching each leg of the number four roof bow to acorresponding main balance link. Furthermore, a first gas strut actsbetween the number four roof bow and the balance link while a secondhydraulic ram, per side of vehicle, moves the number four roof bowthrough a clevis and pin arrangement.

In accordance with the present invention, the preferred embodiment of aconvertible roof actuation mechanism includes a pliable roof cover, atop stack mechanism supporting the roof cover, and at least one roof bowof the top stack mechanism independently movable relative to theremainder of the top stack mechanism for selectively reducing andincreasing tension of the roof cover during latching. Another aspect ofthe present invention provides a single driving mechanism, such as apiston, for each side of the vehicle, to operate both the tensionrelieving roof bow movement and the top stack mechanism movement. In afurther aspect of the present invention, a rigid backlite is attached toa pliable roof cover. Still another aspect of the present inventionprovides a more compact and reliable roof bow locking mechanism andlinkage arrangement. Yet another aspect of the present invention employsmultiple links and a connector to couple an optional number five roofbow to a number four roof bow for simultaneously moving the numbers fourand five roof bows to tighten or loosen the fabric roof.

The convertible roof actuation mechanism of the present invention isadvantageous over conventional devices in that the present inventionreduces drifting of the raised convertible roof away from the frontheader panel and, alternately a tonneau cover, by selectively reducingand then increasing tension or tautness of the roof cover. Furthermore,packaging space of the stowed convertible roof is optimized in thestorage compartment by the linkage movement of a number four roof bow;this allows for placement of a very large and rigid backlite in arelatively small storage compartment, thereby avoiding the creasing anddiscoloration disadvantages commonly associated with folded flexiblebackfires made of plastic. The present invention is also advantageouslyemployed in combination with stationary affixation of the rear edge ofthe roof cover to the body where front header panel latching drift andtension problems are often exacerbated. Moreover, the single drivingmechanism, per side of vehicle, used for operating the tension reducingroof bow and the top stack mechanism is much more cost effective andless failure prone as compared to a more complicated, traditional twopistons/rams per vehicle side. Additional advantages and features of thepresent invention will become apparent from the following descriptionand appended claims, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view showing the preferred embodiment of aconvertible roof actuation mechanism of the present invention;

FIG. 2 is a side elevational view, partially in section, showing thepreferred embodiment of the present invention convertible roof actuationmechanism, with a top stack mechanism disposed in a fully raisedposition and a number four roof bow disposed in an extended position;

a FIG. 3 is an enlarged perspective view, taken within circle 3 of FIG.2, showing the preferred embodiment of the present invention convertibleroof actuation mechanism, with the top stack mechanism disposed in thefully raised position and the number four roof bow disposed in theextended position;

FIG. 4 is an enlarged perspective view, taken opposite FIG. 3, showingthe preferred embodiment of the present invention convertible roofactuation mechanism, with the top stack mechanism disposed in the fullyraised position and the number four roof bow disposed in the extendedposition;

FIG. 5 is a side elevational view, partially in section, showing thepreferred embodiment of the present invention convertible roof actuationmechanism, with the top stack mechanism disposed in the fully raisedposition and the number four roof bow disposed in a retracted position;

FIG. 6 is an enlarged perspective view, taken within circle 6 of FIG. 5,showing the preferred embodiment of the present invention convertibleroof actuation mechanism, with the top stack mechanism disposed in thefully raised position and the number four roof bow disposed in theretracted position;

FIG. 7 is an enlarged perspective view, taken opposite FIG. 6, showingthe preferred embodiment of the present invention convertible roofactuation mechanism, with the top stack mechanism disposed in the fullyraised position and the number four roof bow disposed in the retractedposition;

FIG. 8 is a side elevational view, partially in section, showing thepreferred embodiment of the present invention convertible roof actuationmechanism, with the top stack mechanism disposed in a fully retractedand stowed position, and with the number four roof bow disposed in theretracted position;

FIG. 9 is a diagrammatic side elevational view, showing a firstalternate embodiment of the present invention convertible roof actuationmechanism, with a top stack mechanism disposed in a fully raisedposition and a number four roof bow disposed in an extended position;

FIG. 10 is a diagrammatic side elevational view, showing the firstalternate embodiment of the present invention convertible roof actuationmechanism, with the top stack mechanism disposed in a fully raisedposition and the number four roof bow disposed in a retracted position;

FIG. 11 is a fragmentary side elevational view, partially in section,showing a second alternate embodiment of the present inventionconvertible roof actuation mechanism, with a top stack mechanismdisposed in a fully raised position and number four and five roof bowsdisposed in extended positions; and

FIG. 12 is a fragmentary side elevational view, showing the secondalternate embodiment of the present invention convertible roof actuationmechanism, with the top stack mechanism disposed in the fully raisedposition and the number four and five roof bows disposed in retractedpositions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As can be observed in FIGS. 1 and 2, a soft-top convertible roof for anautomotive vehicle includes a top stack mechanism 21 and a pliable orflexible roof cover 23. Top stack mechanism 21 employs a number one roofbow 25, a number two roof bow 27, a number three roof bow 29 and anumber four roof bow 31. Number one roof bow 25 is preferably integrallycast from an aluminum or magnesium alloy with a pair of front roof rails33. A pair of center roof rails 35 are pivotably coupled to front roofrails 33 by over-center control linkage assemblies 37. Furthermore, apair of rear roof rails 39 are coupled to center roof rails 35 by pivots41. A bottom pivot 51 of each rear roof rail 39 is coupled for movementto a main pivot bracket 53 which is bolted or welded onto a stationarystructure affixed to a body 55 of the automotive vehicle. A pair ofbalance links 57 each have a first end pivotably coupled to bracket 53and a second end pivotably coupled to each center roof rail 35.Over-center control linkage assembly 37 is connected between front roofrail 33 and rear roof rail 39. Accordingly, the convertible roof can beautomatically moved from a fully extended and raised position, as isshown in FIGS. 1 and 2, to a fully retracted and stowed position, as isshown in FIG. 8, within a storage compartment or boot well 61. Boot well61 is longitudinally located between a front occupant seat 63 and atrunk 65. Rear roof rail 39 is preferably die cast and subsequentlymachined from an aluminum or magnesium alloy while balance link 57 andthe roof bows are made from a carbon steel tubing with swaged ends. Mainpivot bracket 53 is stamped from steel or is cast from aluminum ormagnesium.

Roof cover 23 is in a stretched and tensioned condition when theconvertible roof is in its fully raised condition, as is shown in FIGS.1 and 2. In the fully raised position, a single sunroof-type electricmotor actuator 71, centrally mounted to number one roof bow 25, isenergized to push and pull sunroof-type cables 75 for driving a pair ofoutboard rotating latches 73. Latches 73 are rotated along generallyhorizontal, transverse planes to engage latching receptacle structuresmounted to a front header panel 79 disposed above a windshield. Motor 71tensions cables 75 for latching and compresses cables 75 for unlatchinglatches 73 through linear cams (not shown) which each operate in atransverse slide to lift a toggle mechanism for rotating the latch. Thecams are mounted adjacent to each latch 73. A set of microswitches orproximity switches 81 are mounted on number one roof bow 25 to sense theengagement of latches 73 to the front header receptacles, therebydeenergizing motor 71 and also sending an electric signal to amicroprocessor 401, or an analog or solid state based electronic controlunit. Microprocessor 401 then automatically actuates the hydraulicactuator 115 for subsequently moving number four roof bow 31.

In an alternate embodiment, levers (not shown), having bifurcated ends,or bellcranks act in conjunction with fulcrums for downwardly andupwardly pivoting front roof rails 33 relative to center roof rails 35in an automatic manner operably driven by electric motor 71. This leverdevice is disclosed in further detail in U.S. patent application Ser.No. 08/916,821 entitled "Latching and Control Apparatus for anAutomotive Vehicle Convertible Roof," which was invented by SheryarDurrani and was filed on Aug. 22, 1997, and U.S. patent application Ser.No. 08/916,822 entitled "Convertible Roof Actuation Mechanism" which wasinvented by Steven G. Laurain, Michael T. Willard and William A. Sims,and was also filed on Aug. 22, 1997; these patent applications areincorporated by reference herein.

In the preferred embodiment which is illustrated in the present figures,the automated fulcrums and levers are not used to allow for a manualover-center pull down of the number one bow for latching. Since theconvertible roof actuation mechanism of the present invention isessentially symmetrically identical on both sides of the vehicle, onlyone side will be further discussed hereinafter.

Referring now to FIGS. 2, 3 and 4, a straight driving link 101 has apivot 103 mounted on rear roof rail 39. A lower pivot 105 of number fourbow 31 is also pivotably coupled to an opposite pivot 106 of drivinglink 101 by way of a first straight leg 107 of a generally V-shaped bowlink 108. A pivot 109 mounted to a second straight leg 110 of bow link108 is coupled to a yoke 111 attached to an end of a linearly movingpiston rod 113 of a hydraulic fluid powered piston-type actuator. Afollower link 117 has a first pivot 119 coupled to bracket 53 and asecond pivot coupled to both actuator yoke 111 and bow link 108 at pivot109. Stops 121 are affixed to edges of follower link 117. Abutting atapered end of leg 110 of bow link 108 against stops 121 serves to limitthe movement of bow link 108.

A piston cylinder 115 of the actuator is fluidically coupled to ahydraulic pump 123 and is electrically connected to a rear roofrail-to-bracket position sensing microswitch, a front roofrail-to-center roof rail position sensing microswitch, an occupantaccessible top up/down switch and the electronic control unit. Pistoncylinder 115 is allowed to pivot about a pivot point 125 in relation tothe vehicle's body 55.

A locking structure includes a straight and elongated lock 151 having aproximal end pivotably coupled to a median section of driving link 101by a pivot 153. A torsion spring 155 is also centrally mounted aboutpivot 153. Spring 155 has a first arm 157 secured to driving link 101and a second arm 159 secured to an edge of lock 151 for biasing a distalend of lock 151 toward a lock receiving member 161. Lock receivingmember 161 is a circular disk mounted inside yoke 111 coaxially aboutpivot 109. A circular-curved distal edge 163 (see FIG. 7) of lock 151engages the periphery of lock receiving member 161 when the number fourroof bow 31 is fully extended. This serves to maintain number four roofbow 31 in its extended position by deterring links 101 and 117 fromcollapsing or angularly moving toward each other. A disengagement finger165 inwardly extends from a wall of yoke 111. Disengagement finger 165has a generally circular peripheral shape which operably abuts againstand pushes an edge of lock 151 from the locked orientation shown inFIGS. 3 and 4 to the unlocked orientations shown in FIGS. 6 and 7 todisengage lock 151 from lock receiving member 161 in a camming manner.Thereafter, the linkages are allowed to move relative to each other inresponse to the pivoting and linear movement of yoke 111 and piston rod113, when unlocked, thereby retracting number four roof bow 31 to acover tension reducing retracted position. Links 101, 108, and 117, andlock 151 are preferably stamped from sheet steel.

The raising operation of convertible roof will now be discussed ingreater detail with reference to FIGS. 2-8. First, top stack mechanism21 is fully stowed in boot well 61 as is shown in FIG. 8. In thisposition, piston rod 113 is fully withdrawn into piston cylinder 115.When the vehicle occupant actuates an electrical switch, themicroprocessor or other electronic control unit will cause piston rod113 to linearly advance from piston cylinder 115. This advancingmovement of piston rod unfolds links 101, 108 and 117, thereby upwardlyand forwardly pivoting rear roof rail 39 and the remainder of top stackmechanism 21 about rear roof rail pivot 51 and the pivot couplingbalance link 57 to stationary bracket 53.

Next, piston rod 113 and the associated yoke 111 are fully advanced tothe positions shown in FIGS. 5-7. This fully advanced piston rod andclevis orientation causes top stack mechanism 21, except for number fourroof bow 31, to be placed in its fully raised position, while alsoleveraging bow link 108 about pivot 106 of driving link 101 such thatnumber four roof bow 31 is in a retracted and lowered position. Theretracted position of number four roof bow 31 reduces stretching tensionof the fabric cover 23 to reduce the efforts by the vehicle occupant(for a manual system) or an automated over-center mechanism, in pullingdown number one roof bow 25 adjacent to the front header and thesubsequent manual or automated latching operations.

Subsequently, piston rod 113 and yoke 111 are again slightly retractedaway from top stack mechanism 21 and cover 23 to an intermediateposition thereby rotating leg 107 of bow link 108 upward about drivinglink pivot 106. This can be observed in FIGS. 2-4. This action serves tofully extend number four roof bow 31 so as to increase the tension ofcover 23 and provide the desired final fit and finish, and head roomdesired in the convertible roof assembly. It is significant that thelinkage assembly acts in a progressive manner whereby the side rail andtop stack mechanism are first raised and then the number four roof bowis subsequently and independently extended while the rear roof rail andthe remainder of the top stack mechanism are stationarily maintained intheir fully raised positions. The latching of number one roof bow 25 tothe front header assists in stabilizing rear roof rail 39 which acts asa stationary support for pivot 103 of driving link 101. During thisslight retraction of piston rod 113 and yoke 111 to fully extend numberfour roof bow 31, spring 155 serves to bias lock into engagement withlock receiving member 161. The position sensing micro switches orpotentiometers send the appropriate linkage position indicating signalsto the micro processor for controlling advancing and retracting motionof piston rod 113.

It is envisioned that approximately 1/2 inch of piston rod retraction,from its fully advanced position to its intermediate position, willcause approximately 2 inches of linear movement of the number four roofbow, from its retracted position to its extended position, based on thegeometry of the linkage arrangement. The link lengths and geometricpower ratios can be altered for different desired mechanical advantagesand differing travel distances. After front header latches 73 areunlatched and number one roof bow 25 and front roof rail 33 are upwardlypivoted relative to center roof rail 35, piston rod 113 will furtherretract into piston cylinder 115 to return top stack mechanism 21,including number four roof bow 31, to its stowed position.

The linkage positioning and geometry optimizes packaging of the foldedtop stack components and number four roof bow 31 such that a much largerthan standard rigid, glass backlite 201 can be stored within therelatively small sized boot well 61. Backlite 201 has a length of atleast 300 millimeters as measured along a vertical fore-and-aft planeand is three-dimensionally curved, however, number four roof bow 31 isfully retracted forward of a majority of backlite 201 and lower four bowpivot 105 is forward of the adjacent portion of piston rod 113. Backlite201 is secured to roof cover 23 as is disclosed in U.S. patentapplication Ser. No. 08/916,820 entitled "Backlite Retention System forUse in an Automotive Vehicle Convertible Roof," which was invented bySteven G. Laurain and Michael T. Willard, and was filed on Aug. 22,1997; this application is incorporated by reference herein.

FIGS. 9 and 10 illustrate a first alternate embodiment of theconvertible roof actuation mechanism of the present invention whereinthe locking structure includes a toggle mechanism 221. In thisconstruction, a first toggle link 223 is pivotably coupled to drivinglink 101 at a pivot 225. A second toggle link 227 is pivotably coupledto first toggle link 223 at a pivot 229. Second toggle link 227 isfurther pivotably coupled to yoke 111 at pivot 109. Various stops andsprings (not shown) will also be used to limit and bias movement of thetoggle links. Thus, after actuating piston rod 113 has fully advancedand raised rear roof rail 39 to its fully raised position, and pistonrod 113 then partially retracts to rotate number four bow link 107 tothe number four bow extended position (shown in FIG. 9), togglemechanism 221 is moved from the unlocked position of FIG. 10 to theover-center and locked position of FIG. 9. This maintains number fourroof bow 31 in its fully extended cover tensioning position. Adisengagement finger, such as that disclosed in the preferredembodiment, can be employed on yoke 111 to disengagably abut and camtoggle mechanism 221 to an unlocking orientation for retraction ofnumber four roof bow 31.

Referring now to FIGS. 11 and 12, a second alternate embodiment of theconvertible roof actuation mechanism of the present invention employs anoptional number five roof bow 301 movably connected to a rear edge ofroof cover 21. Number five roof bow 301 is used to push the coveroutboard against the side rail and a beltline opening, or to provideadditional roof cover skirt length for slack when retracting. Numberfive roof bow 301 only moves within boot well 62 below the beltline.Furthermore, number five roof bow 301 is movably coupled to number fourroof bow 31 by way of a connector 303. It is envisioned that connector303 is a flexible cable having a first eye 305 pivotably riveted to amiddle section of number four roof bow 31 and having a second andoppositely disposed eye 307 pivotably riveted to a middle section ofnumber five roof bow 301. Number five roof bow 301 is also pivotablyjournalled about stationary bracket 53. Thus, when number four roof bow31 is moved from its retracted position as shown in FIG. 12 to itsextended position as shown in FIG. 11, number five roof bow 301 willrise or extend in concert with number four roof bow 31. This furtherreduces convertible cover tensioning during fastening of the number oneroof bow to the vehicle body.

While various aspects of the convertible roof actuation mechanism havebeen disclosed, it will be appreciated that many other variations may beemployed without departing from the scope of the present invention. Forexample, multiple roof bows can be moved independently from theremaining fully raised and static top stack mechanism to selectivelyreduce and increase the roof cover tension thereby assisting withlatching and pull down efforts. Furthermore, additional or fewerlinkages of similar or alternate shapes may be employed to perform thepresent invention's specified functions. It is alternately envisionedthat an electric motor actuator can be employed to directly move thedisclosed linkages or other mechanically advantageous members for movingthe number four roof bow relative to the remainder of the top stackmechanism, in place of a linear hydraulic actuator. The top stack canalternately be manually raised and retracted without any actuator, andthe number one roof bow can employ manual J-hook style latches. Otherrigid or flexible number four-to-five roof bow connectors can also beemployed. Moreover, other locking structures can be used to preventundesired collapsing of the linkage arrangement when the extendable roofbow is in its desired position. The disclosed lock and lock receivingmember can also be reversibly mounted. Various materials and linkageshave been disclosed in an exemplary fashion, however, other materialsand linkages may of course be employed. It is intended by the followingclaims to cover these and any other departures from the disclosedembodiments which fall within the true spirit of this invention.

The invention claimed is:
 1. A convertible roof system for an automotivevehicle, said system comprising:a pliable roof cover; a top stackmechanism including a tensioning roof bow and a roof rail, said roofcover being supported by said roof bow, said top stack mechanism andsaid roof cover being movable from a stowed position to a raisedposition; an automatic powered actuator to operably move said top stackmechanism; a first link coupling said roof bow to said actuator; and asecond link coupling said first link to said roof rail; selectiveenergization of said actuator causing said roof bow to move from a bowretracted position to a bow extended position while the remainder ofsaid top stack mechanism is located in its fully raised position;movement of said roof bow increasing tension of said roof cover whensaid roof bow is in its extended position.
 2. The system of claim 1further comprising a locking structure pivotably mounted to at least oneof said links operably acting to secure said roof bow in said extendedposition, a lock disengaging member moving with a portion of saidactuator selectively contacting and moving said locking structure. 3.The system of claim 2 further comprising:a spring biasing said lockingstructure relative to said at least one of said links; a lock receivingmember moving with said portion of said actuator; and an end of saidlocking structure disengagably contacting against said lock receivingmember when said roof bow is in said extended position.
 4. The system ofclaim 2 wherein said locking structure includes a toggle linkagearrangement coupling said actuator to at least one of said links.
 5. Thesystem of claim 1 wherein:(a) said actuator fully advances to drive saidtop stack mechanism from its stowed position to its fully raisedposition; (b) said roof bow is in a retracted position when saidactuator is fully advanced; and (c) said actuator subsequently retractsto an intermediate position thereby moving the height of said roof bowto its fully extended position while maintaining the raised position ofsaid roof rail.
 6. The system of claim 5 further comprising a poweredlatching device mounted to a forward portion of said top stackmechanism, and a sensor sending a signal to an electronic unit connectedto said powered actuator for indicating a predetermined top stackmechanism-to-body condition to control advancing and retracting movementof said actuator and said roof bow.
 7. The system of claim 1 whereinsaid top stack mechanism includes:a number one roof bow; a number tworoof bow; and a number three roof bow; said tensioning roof bow being anumber four roof bow which is movable without substantial movement ofsaid roof rail and said number one, two and three roof bows when saidroof rail and said number one, two and three roof bows are maintained intheir fully raised positions.
 8. The system of claim 7 furthercomprising:a front seat; a trunk; a storage compartment disposed betweensaid front seat and said trunk; and a three-dimensionally curved glassbacklite fastened to said cover, said cover and said backlite beingretractable into said storage compartment.
 9. The system of claim 1further comprising:a bracket stationarily mounted to said vehicle; apivot of said roof bow coupled to said actuator by said first link; anda third link pivotably coupling said actuator and said first link tosaid bracket.
 10. The system of claim 1 further comprising a number fiveroof bow of said top stack mechanism movable from a retracted positionto an extended position in concert with said tensioning roof bow afterthe remainder of said top stack mechanism is in its fully raisedposition, said number five roof bow being substantially horizontal whenin its extended position.
 11. An automotive vehicle comprising:astationary bracket; a rear roof rail having a pivot, said pivot beingcoupled to said bracket, said rear roof rail being elongated in asubstantially vertical direction when raised; a roof bow having a pivot;a linkage assembly coupling said pivot of said roof bow to said rearroof rail and said bracket; a balance link pivotably coupled to saidbracket; and a single powered actuator on each side of the vehiclecoupled to and driving said linkage assembly for moving said roof bowwithout substantially moving said balance link and said rear roof rail,said single powered actuator on each side of the vehicle alsoselectively moving said rear roof rail.
 12. The vehicle of claim 11further comprising a locking structure operably maintaining the positionof said linkage assembly relative to said rear roof rail when said roofbow is in its extended position.
 13. The vehicle of claim 12 furthercomprising:a roof cover; a lock receiving member mounted on a movableend of said actuator; and a free distal end of said locking structuredisengagably contacting against said lock receiving member when saidroof bow is in an extended position for tensioning said cover.
 14. Thevehicle of claim 13 further comprising a spring biasing said lockingstructure relative to said linkage assembly.
 15. The vehicle of claim 12further comprising a disengagement member movable in concert with aportion of said actuator, said disengagement member operably disengaginga portion of said locking structure from a portion of said linkageassembly to allow movement of said roof bow independent from said rearroof rail when it is desired to retract said roof bow.
 16. The vehicleof claim 11 further comprising:a linearly moving piston rod of saidactuator; a yoke of said actuator mounted to said piston rod; a pivotingfour bow locking structure; a four bow lock receiving member moving withsaid yoke; and a disengagement member mounted on said yoke forselectively abutting against and disengaging said pivoting four bowlocking structure from said four bow lock receiving member.
 17. Thevehicle of claim 12 when said locking structure includes a togglelinkage arrangement coupling a portion of said actuator to one of saidlinks.
 18. The vehicle of claim 11 further comprising:a center roof railpivotably coupled to said rear roof rail, said balance link couplingsaid center roof rail to said bracket; and a number three roof bowcoupled to one of said roof rails by a pivot.
 19. The vehicle of claim11 wherein said linkage assembly includes:a first link coupling saidroof bow to a pivot of said actuator; a second link pivotably couplingsaid first link to said rear roof rail; and a third link coupling apivot of said first link, substantially opposite from a pivot of saidroof bow, to a pivot of said bracket; said third link also coupling saidpivot of said actuator to said bracket.
 20. The vehicle of claim 19wherein said first link has a substantially V-like shape, said roof bowis a number four roof bow.
 21. A convertible roof actuation mechanismfor use in an automotive vehicle, said mechanism comprising:a top stackmechanism including a roof rail; a linkage assembly having a first linkand a second link; a roof bow forming part of said top stack mechanismand being movably driven independent of the remainder of said top stackmechanism by said linkage assembly when said top stack mechanism is in afully raised position; a lock having a first end movably coupled to oneof said links; a lock receiving member movable in concert with a portionof said second link, a second end of said lock selectively engaging withsaid lock receiving member to maintain the positional spacing of saidfirst and second links while serving to maintain said roof bow in apredetermined position relative to the remainder of said top stackmechanism; and a disengagement member operably causing said lock todisengage said lock receiving member when it is desired to move saidroof bow relative to the remainder of said top stack mechanism.
 22. Themechanism of claim 21 further comprising a spring biasing said lockrelative to one of said links.
 23. The mechanism of claim 22 wherein anend of said lock which engages said lock receiving member has a curvedshape corresponding to a curved shape of said lock receiving member. 24.The mechanism of claim 21 further comprising an automatically poweredactuator coupled to said linkage assembly for operably moving said atleast one roof bow, said lock receiving member and said disengagementmember being mounted on a moving end of said actuator.
 25. A convertibleroof actuation mechanism for use in an automotive vehicle, saidmechanism comprising:a roof cover; a top stack mechanism supporting saidroof cover; a number four roof bow; a linkage assembly coupling saidnumber four roof bow to said top stack mechanism; and a toggle linkarrangement coupled to said linkage assembly and serving to selectivelylock said number four roof bow in an extended position relative to saidtop stack mechanism; said number four roof bow being retractable toreduce tension of said roof cover, even when said top stack mechanism isin a fully raised position, if said toggle linkage arrangement islocated in an unlocked orientation.
 26. A convertible roof actuationmechanism for use in an automotive vehicle having a convertible roofstorage compartment, said mechanism comprising:a flexible roof cover; anumber one roof bow attached to a front edge of said cover; a number tworoof bow supporting said cover; a number three roof bow supporting saidcover; a number four roof bow supporting said cover and being movablewhile said number two and three bows are substantially stationary; and anumber five roof bow affixed to a rear edge of said cover, said numberfive roof bow being movable in said storage compartment when said numbertwo and three bows are substantially stationary; wherein movement ofsaid number four and five roof bows serve to reduce tautness of saidroof cover when moved independently of said number two and three roofbows.
 27. The mechanism of claim 26 further comprising a connectorconnecting portions of said number four and five roof bows at locationsspaced away from pivots of said bows for concurrent movement of saidnumber four and five roof bows.
 28. The mechanism of claim 27 furthercomprising:a side rail assembly coupled to said number one, two andthree roof bows; a linkage arrangement coupling said number four roofbow to said rail assembly; and a single automatically powered actuator,per side of vehicle, coupled to said linkage arrangement for selectivelymoving said number four and five roof bows independently of said numbertwo and three bows.
 29. The mechanism of claim 28 further comprising:arigid backlite affixed to said cover; said single actuator, per side ofvehicle, serving to raise said side rail assembly and subsequentlyindependently move said number four and five roof bows.